1. Field Of The Invention
The field of the present invention generally relates to bar code scanning apparatus. More particularly, the field of the present invention relates to a method and apparatus for preferentially aligning the surfaces of an item with respect to a predetermined locus of positions defining an optimal scanning path for decoding a bar code label.
Bar code scanners are well known for scanning the universal product code ("UPC") and other types of bar codes on packages or containers, particularly in retail stores Generally, in retail stores, bar code scanners are set up at check-out stands or are built into a horizontal check-out deck so that a laser beam is scanned up through a transparent window, defining a number of different scan lines. Normally, packages are placed by the customer on a counter, deck or conveyor. A check-out person then takes each package, visually locates the UPC or other bar code label on a surface of the package and moves the package through the laser's scanning area. A disadvantage of this technique is that the label must first be found and then the package must be held in a particular orientation in order to effect an accurate reading by the laser scanner decoding the bar code lines as the bar code moves through the scanning area. Misalignment of the bar lines, or inadvertent movement of the package during the scanning operation can result in a misreading of the bar code.
Conventional attempts to minimize or eliminate the participation of check-out personnel include a device such as described in U.S. Pat. No. 4,939,355. There, an item transported by a moving conveyor is subjected to a complex series of different scan patterns approaching from different sides of the item. This scanning requires a large depth of field for the scan beams. The item to be scanned is placed in any orientation on the scan belt. A scanning means generates scan lines in an X configuration for reading the object in virtually any orientation. Due to the infinite variations in product sizes, irregularities of shapes and differing locations of a bar code label on an item, conventional scanning methods too frequently fail to achieve a first successful read on the pass of the item scanned, which requires rescanning to obtain the data associated with the bar code label being decoded.
Additionally, conventional methods for bar code scanning provide the customer with an itemized listing, such as receipt list, of the items which were scanned. There is a time lag between the time that the items are scanned and the point at which the customer receives the itemized list. This often results in a lack of customer recognition of the items and their associated prices The lack of recognition inherent in a list, disassociated from the items as they are moving on a scanning path, leads to customer misunderstanding and may slow down the check-out process at a retail point of sale.
Another problem associated with conventional automated scanning systems involves security. For example, in the method described in U.S. Pat. No. 4,676,343, the customer must look for each label and then scans the item in the conventional manner. The item is then placed on a conveyor belt for transport and item verification. This system is very slow because of the inexperience of the customer and because of the difficulty in finding the label. This method also does not provide adequate security because the customer can place a higher priced similar item on the belt.
An additional problem in a conventional automated scanning system is a substantial number of "no reads" when an item is not positioned properly in the scanning region. When an item has an irregularly shaped surface, the rate of no-reads tends to be higher for conventional automatic scanning systems.
Accordingly, what is needed is a system for completely stabilizing an item as it is moved along an item path through a scanning region It also would be desirable to register two surfaces of an item to be scanned such that the bar code labels are preferentially positioned in a predetermined, optimal alignment with the scanning lines of a laser bar code scanner.
What is also needed is a method for automatically locating at least two surfaces of a package to be scanned such that the two surfaces are stably registered with respect to a predetermined locus of positions which define an optimal scanning path for a bar code scanner.
What is needed is a system for optimally scanning a bar code label which would increase the first pass read rate to facilitate the checking out of items at a point of sale such as a grocery market check-out area. In this regard, what is also needed is a system for optimally scanning bar code labels on surfaces of an item which are stabilized with respect to an optimal scanning path and which limits the number of directions from which the surfaces of an item are scanned. This advantageously would simplify the scanning process and increase the speed and accuracy of the scanning.
What is also needed in the operation of an automated retail point of sale scanner is a display means for providing a concurrently moving display of pricing data relating to the item being scanned as the item is moved along the item path through a scanning region. This would enhance customer recognition of pricing data with the item purchased and would facilitate the check out process.
The invention facilitates a system of check-out without a check out clerk. In this process, the customer places his or her items on the conveyor belts and they are scanned without the customer having any further contact until the goods are paid for. Items not read may be handled in one of several ways as described in U.S. Pat. No. 4,939,355.